A number of doctors, hospital officials and other healthcare workers have tested positive for Covid-19 even after taking two doses of a vaccine against the disease. However, all of them are either asymptomatic or have mild symptoms, doctors and health department officials said.

There are also a few reports of people above 60 testing positive for Covid-19 after getting the first dose of a vaccine.

Health department officials and doctors said a vaccine could not have 100 per cent efficacy and so one should not drop guard even after getting two doses.

A senior doctor at the Institute of Post-Graduate Medical Education and Research-SSKM Hospital tested positive for Covid-19 a few days ago and is being treated at the Infectious Diseases and Beleghata General Hospital. She had earlier tested positive for the coronavirus in November.

“She took two jabs of a Covid vaccine at SSKM Hospital and didn’t report any strong after-event of immunisation,” said a health department official.

A few days back, she started complaining of weakness and shortness of breath and decided to go for a second test for the virus. The test returned positive on Thursday morning and she was admitted to the Beleghata hospital in the afternoon.

In the evening doctors said her condition was stable. “We will carry out genomic sequencing and several other tests of her swab sample,” the official said.

Senior officials said they were in talks with the Indian Council of Medical Research over whether the doctor’s samples would be sent to the National Institute of Biomedical Genomics in Kalyani or some other institute.

Apart from those who received both doses of a vaccine, there are people who got infected with the virus after getting the first dose.

Four or five persons who tested positive for Covid after getting the first dose of a vaccine have been admitted to AMRI Hospitals Dhakuria since March 1, the day vaccination of senior citizens and people above 45 with comorbidities started.

“None of them had to be admitted to the intensive care unit and all have been discharged,” an official of the hospital said. “One of our healthcare workers had tested positive for Covid after getting the first dose of a vaccine. The person was asymptomatic and stayed at home.”

A senior official of a private hospital who had taken both doses of a Covid-19 vaccine in February tested positive for the virus and is now in home isolation. The official, who has comorbidities, is asymptomatic.

In India, two Covid vaccines have been granted emergency use approval — Covishield and Covaxin.

The efficacy of Covishield, manufactured in the country by the Serum Institute of India, varies between 63 and 70 per cent, experts said.

The manufacturers of Covaxin, Bharat Biotech, have said the vaccine has 81 per cent efficacy.

“It has been established that around 70 per cent of the people who received both doses of a vaccine can still be infected but will have mild or no symptoms. The rest 30 per cent of the vaccine recipients can get mild to severe symptoms,” said Ajay Chakraborty, the state’s director of health services.

“That means, even after taking both doses of a vaccine, one should not drop guard and keep wearing masks and maintain social distancing,” he said.